A liquid ejection apparatus, e.g., an inkjet head, includes a channeled substrate and a reservoir formation substrate. The channeled substrate includes a plurality of pressure chambers and a communication portion that is shared by the pressure chambers and communicates with the pressure chambers. A vibration plate is disposed on the upper surface of the channeled substrate, to cover the pressure chambers and the communication portion. The vibration plate includes a plurality of piezoelectric elements in correspondence with the pressure chambers. A nozzles plate is disposed at the lower surface of the channeled substrate opposite to the vibration plate. The nozzles plate has a plurality of nozzles communicating with the respective pressure chambers.
The reservoir formation substrate is disposed above the channeled substrate to cover the piezoelectric elements. The reservoir formation substrate is bonded with an adhesive at an area of the vibration plate outside the piezoelectric elements. The reservoir formation substrate includes a reservoir portion. The reservoir portion communicates with the communication portion of the channeled substrate, via a communication opening formed in the vibration plate. Ink in the reservoir portion is supplied to the communication portion of the channeled substrate. In the channeled substrate, the ink is distributed from the communication portion to the pressure chambers.
Contact portions protruding from the vibration plate are disposed at bonding areas of the vibration plate with the reservoir formation substrate outside the piezoelectric elements. A band-like contact portion is disposed all around an end portion or an edge portion of the channeled substrate. Another band-like contact portion is disposed around the communication opening of the vibration plate. The communication opening brings the reservoir portion of the reservoir formation substrate and the communication portion of the channeled substrate into communication with each other. The reservoir formation substrate is bonded to the vibration plate with an adhesive while being pressed against the contact portions. Thus, the channeled substrate and the reservoir formation substrate are favorably bonded.
Each contact portion includes a laminated body having the same layer structure as the piezoelectric element. More specifically, each contact portion includes a piezoelectric layer and two kinds of electrode layers sandwiching the piezoelectric layer from above and below. The layers of the contact portion are separated from those of the piezoelectric element. In other words, the electrode layers included in the contact portion are separated from the electrodes of the piezoelectric element.
In the liquid ejection apparatus, a channel portion (e.g., communication portion) configured to distribute ink to the pressure chambers is formed on a lower channeled structure (e.g., the channeled substrate), together with the pressure chambers. In other words, ink is supplied from an upper channeled structure (e.g., the reservoir formation substrate) to the communication portion of the lower channeled structure (e.g., the channeled substrate), via the communication opening formed on the vibration plate. Thereafter, in the lower channeled structure, ink is distributed to the pressure chambers.